1. Field of the Invention
This invention relates to an extruded frame member for forming a frame such as a sash.
2. Prior Art
One conventional molded frame material, as disclosed in Japanese Patent Application Laid-Open (Kokai) No. 57-197385 comprises a molded body having sheet-like walls and a plurality of reinforcing elements either embedded in or fused to the sheet-like walls, the reinforcing element being composed of a bundle of fibers joined together by a thermoplastic resin. This molded frame member is produced by extrusion. For forming a frame such as a sash, using a plurality of frame members, obliquely-cut ends of the frame members are butt-jointed by hot plate welding or fusing. During this butt-jointing, the ends of the frame members which are heated and softened are pressed against each other, and at this time the ends of the reinforcing fiber bundles are also pressed against each other, so that these ends are caused to be bent or deformed since the thermoplastic resin binding the fibers are softened. As a result, the reinforcing fiber bundles will not appear at a line of joint between the two frame members even after a welding or fusing bead formed along the joint line is removed.
However, the above conventional frame member has the following disadvantages:
(i) First, when extruding the frame member, the thermoplastic resin binding the fibers of the reinforcing element together becomes soft, so that the fiber bundle tends to become loose. Particularly, in the case where the reinforcing fiber bundle is embedded in the wall of the molded body, the embedded reinforcing fiber bundle can not be accurately positioned relative to the wall. Incidentally, it is considered that the main reason why the thermoplastic resin is used to bind the reinforcing fibers together is that the ends of the two reinforcing fiber bundles, when pressed against each other, can be easily bent or deformed because of the softening of the thermoplastic resin binding the fibers, thereby preventing the reinforcing fibers from appearing at the butt-joint of the two frame members.
(ii) Secondly, when the two frame members are butt-jointed together by hot plate fusing, the deformation of the ends of the reinforcing fiber bundles pressed against each other occurs together with the deformation of their respective molded bodies of a thermoplastic resin. And, since the reinforcing fibers and the molded body are different in deformation behavior from each other, it is rather difficult to fuse the two frame members uniformly along a line of the butt-joint. Particularly, in the case where the reinforcing fiber bundle is embedded in the wall of the molded body, extreme care must be exercised to prevent an outer surface of the wall, exposed to an external view, from being deformed during the fusing. In addition, since the butt-jointed reinforcing fibers are not fused together, the area of fusing or bonding is reduced by an amount corresponding to the cross-sectional area of the reinforcing fiber bundles. Therefore, to compensate for this, it is necessary to increase the thickness of the wall of the molded body.
(iii) Thirdly, if the wall of the molded body in which the reinforcing fiber wire is embedded is relatively thin, a stripe appears on the outer surface of the wall, exposed to an external view, along the embedded reinforcing fiber bundles due to the uneven flow of the resin. This detracts much from the appearance of the resultant frame. On the other hand, if the thickness of the wall is increased to overcome such a difficulty, this requires added material and is uneconomical.